Roller furling arrangements for sails give the possibility of adapting the useful surface to the force of the wind, permitting navigation under the best conditions of efficiency and of security.
The roller element is a tubular member through which runs the stay which, while supporting the sail, connects the top of the mast to the bow of the boat.
This tubular member provides a longitudinal slot intended to receive and retain the edge of the sail generally provided with a reinforcing member referred to as the bolt rope. Most often, in order to permit the simultaneous furling of two sails, the roller element comprises two parallel slots. At the same time two such slots facilitate sail changes while the boat is underway. Finally, the lower end of the furling element is connected to a drive mechanism enabling rotation of the element around the stay in order to roller furl the sail.
Roller furling arrangements available at the present time are generally formed from a series of hollow elements which are fixed end to end by a system of notches enabling the transmission of a rotational couple.
This conception of a sail furling arrangement gives the disadvantage of being not very reliable since there are important torsion stresses appearing at the place of connection between two consecutive elements during furling, bringing about rapid wear of the arrangement. On the other hand, under the pressure of the wind, the roller element does not present a resistance to bending which is entirely satisfactory whereby the sail, on being rolled up may form folds and lumps and so bring about its rapid deterioration. Finally, in order to assure a system having sufficient strength, the element of the roller element must have relatively thick walls and thereby considerable weight, this constituting an obvious disadvantage.
The present invention has as its purpose to provide a roller furling element for a sail which avoids the disadvantages of the known systems, thus, it is light and at the same time resistant as much to torsion as to bending.